Elastic yarn



W. D. SMITH July 9, 1940.

ELASTIC YARN Filed Dec. 21, 1939 Patented July 9, 1940 UNITED STATES PATENT OFFICE 2 Claims- This invention relates to elastic yarns of the type which includes a continuous strand or thread of cut or extruded rubber (latex) and at least one inelastic thread, i.e., a thread composed of intertwisted natural vegetable or animal fibres such as cotton, fiax, wool, etc., or wherein the inelastic thread is in the form of a continuous filament or strand of synthetic material, such as Rayon, Nylon, etc., or formed of short pieces in thereof spun together alone or intermixed and twisted with natural animal or vegetable fibres to form the thread.

Usually elastic composite yarns are constructed with two of the so-called inelastic threads wound [3 in opposite directions, in successive layers respectively, around the elastic strand or core thread,

While such core thread is maintained in a strictly rectilinear state, to form a covering for the latter. Such covered rubber yarns are commonl g referred to as lastex.

Covered rubber yarns have many well-known faults and inadequacies, such as relative slippage between the covering thread or threads and the rubber core, in use or when the composite yarn is is being knitted, woven or braided into a fabric, with frequent: breakage of one or the other of the component elements of the yarn under tensional strains.

When a fabric containing covered rubber yarn 0 is cut, or when the covered rubber yarn is cut or the rubber breaks at any point throughout the length of the composite yarn, the rubber core thread, which is normally under a tension, retracts for quite a distance from the point of ;5 cut into the tube-like outer covering composed of the inelastic thread or threads.

In other instances the covering has been composed of a roving formed of animal or vegetable fibres and having substantially no twist, with a to view toward producing maximum coverage of the rubber core. Due to the relative looseness of the fibres of such coverings, a large amount of lint is collected at the guide eyes through which the composite yarn passes in being fed to the needles of a knitting machine, or in being drawn from a shuttle in weaving, etc., during incorporation of the covered rubber yarn in a fabric, resulting in breakage of the yarn.

Due to the fact that during the production of covered rubber yarns, as known to the prior art, thecovering thread is laid in closely adjacent convolutions around the rubber core, in many instances with a second covering thread correspondingly laid around the initial covering in a 5 direction opposite to the laying of the initial covering, speed of production is relatively slow and the yardage per pound relatively low.

One object of the present invention is to provide a composite elastic yarn which will eliminate relative slippage between the threads and the re- 5 traction of the rubber strand relative to the inelastic component of the yarn when the yarn is cu Another object of the invention is to construct the composite yarn in such a manner that the speed of production will be materially increased, for example, in excess of 50% over and above maximum production under the prior art methods.

Another object of the invention is to construct M the composite yarn in such a manner that the gardage per pound Will be increased substantially In producing a composite yarn under the principles of the present invention, an inelastic thread of predetermined count, diameter, or cross-sectional area, is interspun or intertwisted with a continuous strand of rubber, either cut or extruded and of the same or larger or smaller cross sectional area than the inelastic thread, in such a manner that the ultimate composite yarn is formed of closely axially compacted interlocking alternating convolutions of the two threads. The inelastic thread has in it an initial twist of a predetermined nuinber of turns per inch in one direction, and the rubber thread is given an initial twist of a predetermined number of turns per inch in the direction opposite to the twist of the inelastic thread. The two threads are intertwisted or interspun in a direction consistent with that of the initial twist of the inelastic thread and the intertwisting of the two threads together is eifected at a predetermined number of turns per inch.

- In the accompanying drawing Fig. 1 diagrammatically illustrates a piece 01' the inelastic yarn, shown as having an initial twist in one direction throughout its length;

I Fig. 2 illustrates a piece of the rubber thread, with an initial twist in a direction opposite to that of the inelastic thread;

Fig. 3 illustrates the two threads interspun or intertwisted together in a direction consistent with the twist of the inelastic thread: 7

Fig, 4 is'a view similar to Fig. 3 illustrating two inelastic threads intertwisted with a single strand of rubber; and I Fig. 5 diagrammatically illustrates an apparatus for producing composite elastic yarns in accordance with the principles of the present invention.

As shown in Fig. 5, a naked rubber thread A is first wound on the core I of a spool 2, between the end flanges 3 and 4 thereof, without any twist whatsoever being put in the rubber strand A. The spool 2 is mounted on and revolves about a vertically disposed stationary spindle 5, at a predetermined speed, for example about 6000 R. P. M. The rotation of the spool 2, is efiected by any suitable means, such as a pulley 6 loosely mounted on the spindle 5 and a belt 1 connecting the pulley 6 with a suitable source of rotary motion.-

Lying on top of the flange 4 of the spool 2 is a central disc 8. From the disc 8 extends a 'light arm, such as a wire 9. The arm 9 is provided, adjacent its outer end, with an eye or flyer l0 through which the rubber strand A passes from the spool 2 to the bore of a tubular spindle II which is mounted above the spindle 5, in axial alignment therewith.

The hollow spindle II is secured in any suitable kind of rigid support l2 against rotation. Rotatably mounted on the hollow spindle H is a pulley l3 which is driven by a belt M, from any suitable source of power, in a direction opposite to the direction of rotation of the spool 2 on the spindle 5 at a speed of about 8000 to 12,000 R. P. M. Carried by thepulley I4 is a spool l5 upon which is wound the inelastic thread B, said thread having an initial twist of a predetermined number of turns per inch, as illustrated in Fig. 1. The bulk of the inelastic yarn B is wound on the core N5 of the spool l5 between the end flanges l1 and I8 thereof.

Resting on the upper flange is of the spool I5 is a central disc I9 which is provided with an arm 20 having an eye or fiyer 2| adjacent its outer end through which the inelastic yarn B passes, at an angle to the thread A, from the spool l5 to a point X above the upper end 22 of the hollow spindle ll. At the point X the converging threads A and B meet and are intertwisted with each other.

As a matter of illustration, the spool 2 is rotated in a clock-wise direction, as viewed from above, which puts a right-hand twist in the rubber A, as illustrated in Fig. 2. Before being wound on the spool l5, the thread B, in the course of its manufacture, has been given a left-hand twist, as illustrated in Fig. 1, and because thereof the spool I5 is rotated in a counter-clockwise direction, as viewed from above, or, in other words, in a direction opposite to the direction of rotation of the spool 2 and consistent with the initial twist of the inelastic thread B.

The right-hand twist of the elastic rubber thread A meeting the left-hand twist of the inelastic fibrous thread B, at the point X, with the spool traveling in a counter-clockwise direction, causes the two converging threads A and B to intertwist together in the manner illustrated in Fig. 3, i. e., with alternating convolutions of the respective threads A and B closely compacted axially of the composite yarn C with the convolutions being of the left-hand variety.

The right-hand twist of the rubber A reacting against the left-hand twist of the inelastic thread B, during the left-hand twisting of the two together, causes the convolutions a and b of the rubber thread A and inelastic thread B to interlock with each other and in so doing prevent the composite yarn C produced thereby from kinking in future use. Obviously the directions of twist and intertwist, above described, may be reversed and the speed of rotation of the two spools 2 and I5 varied as desired, without departing from the present invention.

On each of the spindles 5 and Il, above and bearing upon the central discs 8 and I9 respectively, are weights 23 and 24 respectively. These weights tend to retain the discs 8 and I9 in frictional contact with the flanges 4 and I8 respectively of the spools 2 and I5, toinsure rotation of the arms 9 and and their respective flyers with the spools 2 and I5 respectively, while providing for restricted or retarded relative rotation between said discs and said spools. 1.1 the case of the rubber strand A the weights 23, of

which there may be one or more, and which are interchangeable or applied in units to produce the particular weight desired to place more or I less restriction upon the relative rotation between the eye or flyer I0 and spool 2, controls the tension on the rubber strand A as it is drawn from the spool by winding of the composite yarn C on the ultimate reel or cone.

The winding of the finished composite yarn C may be accomplished by any of the well-known devices employed for this purpose in the art.

The number of rotations per minute of the spool 2 and fiyer l0 and the speed of take up of the finished yarn C from the point X, which may be at the rate of 75 to 85 inches per minute,

for example, determines the extent of twist put into the rubber A, which, for practical purposes, with a rubber of normally .008 inch in diameter for example, may be approximately 6 to 12 turns per inch. Thus, the degree of extensibility of the rubber A going into the composite yarn C is rather accurately controlled, it being noted that at thepoint X intertwisting of the threads A and B together, the rubber A is under tension and in a stretched condition to a predetermined degree.

In a like manner the inelastic thread B is retained at a certain amount of tension when the intertwisting thereof with the rubber thread A takes place at the point X, and this is controlled by the amount of weight 24 placed on the spindle H above the disc I9, so that the relative rotation between the eye or flyer 2i and the spool 15 may be accurately controlled.

If desired, a second inelastic thread, shown at D in Fig. 4, may be twisted with the threads A and B at the point X, as by running two ends from a single spool l5 through the fiyer 2| or from separate spools superimposed upon each other on the spindle II, with both threads running concurrently to and through the fiyer 2 I.

As a result of the above operations and as shown in Figs. 3 and 4, the composite yarn C is made up of rather tightly interlocking alternating convolutions .a and b of the threads A and B respectively, and as a result of such relatively tight intertwisting the inelastic thread can not slip relative to the elastic thread, regardless of the number of times the composite yarn may be stretched and permitted to retract. The expansion and contraction of the components A and B of the composite yarn C react coordinately. The inelastic thread B governs the maximum stretch of the composite yarn C, but even tions again become closely compacted one with the other axially of the yarn C, as shown in Fig. 3. With this arrangement, the inelastic thread in the composite, yarn tends to hide or at least detract from the prominence of the intertwisted rubber thread A, so that. in a fabric knitted, woven, or braided, in which the composite yarn C is incorporated, the rubber is relatively obscure and the fibrous inelastic thread is relatively prominent. This may be further accentuated by the character of the inelastic thread B employed. For example, the smaller the initial twist in the inelastic thread B the greater the rubber obscuring qualities thereof. Likewise, variations in diameters between the elastic yarn and the inelastic yarn may be utilized to increase the relative obscurity of the rubber with respect to the inelastic thread in the finished composite yarn and the fabric in which such yarn is incorporated.

I claim: I 1. A composite yarn comprising an elastic thread and an inelastic thread respectively formed into successive convolutions alternately intertwined with each other in closely compacted relation axially of said yarn with the elastic thread having an initial twist in a direction opposite to that of the intertwisting of said two threads together.

2. A composite yarn comprising an elastic thread and an inelastic thread respectively formed into successive convolutions alternately intertwined with each other in closely compacted relation axially of said yarn with the elastic.

threadhaving an initial twist in a direction onposite to that of the intertwisting of said two threads together and with the inelastic thread having an initial twist in a direction consistent with that of said intertwisting.

WILBERT D. SMITH. 

